Prognostic prediction ability of postoperative multifocal ERG after vitrectomy for diabetic macular edema.

PURPOSE: Diabetic macular edema (DME) causes visual loss in diabetic patients. Multifocal electroretinograms (mfERGs) have been used to assess macular function pre- and postvitrectomy for DME. METHODS: A standard three-port pars plana vitrectomy with peeling of inner limiting membrane was performed in 25 eyes of 21 patients (13 male, 8 female) with DME. For each patient, visual acuity examination, measure of retinal thickness (using optical coherence tomography), and mfERGs were performed before and 1 week, 1 month, 3 months, and 6 months after vitrectomy. RESULTS: Mean postoperative visual acuity was significantly improved (p<0.05, t test), with mean increase of 0.17 logMAR units; mean retinal thickness was significantly (p<0.001) decreased after surgery (from 537 microm to 298 microm). The increase of normalized amplitude of central ring was not significant; the mean P1 wave-amplitude increased from 0.33 to 0.40 mV; mean P1 wave-implicit time decreased 2.88 ms. We divided the patients into two groups: Group 1 (13 eyes), in which the visual recovery was less than 0.20 logMAR, and Group 2 (12 eyes), in which the visual recovery was greater than 0.20 logMAR. ERG results were statistically significantly different between the groups (p<0.025), when we consider the response recorded from the central ring. In Group 2 there is a marked reduction in implicit time of both ERGs waves, which was statistically significant for N1 wave (p=0.01). The changes of parameters of mfERG observed 6 months after surgery were consistent with those recorded just 1 week after surgery. CONCLUSIONS: Multifocal electroretinogram can be useful to predict functional prognosis in patients with diabetes who underwent vitrectomy for diabetic macular edema.

Three-port lens-sparing vitrectomy for aggressive posterior retinopathy of prematurity: early surgery before tractional retinal detachment appearance.

PURPOSE: Aggressive posterior retinopathy of prematurity (APROP) may suddenly develop into tractional retinal detachment (TRD), often resulting in poor vision if untreated. The aim of the current study is to examine the anatomic results and complications of lens-sparing vitrectomy (LSV) for stage 3 APROP, before TRD appearance. METHODS: A retrospective, noncomparative, consecutive case series of 13 eyes of 9 patients (mean gestational age 24.1+/-0.9 weeks [range: 23-25 weeks], mean birthweight of 725.8+/-107.9 grams [range: 598-897 grams]) with stage 3 APROP was carried out. The eyes did not respond to at least one session of retinal laser photocoagulation, showing signs of disease progression. All eyes underwent 20-gauge LSV before retinal detachment appearance. RESULTS: All eyes underwent 20-gauge three-port LSV and intraoperative additional laser photocoagulation. At the end of the surgery, five eyes were tamponaded with air; in eight eyes, a balanced salt solution was left in the vitreous cavity. After 13.5+/-5.3 months of follow-up (range: 4-22), the retina was completely attached in all eyes, without any signs of progression. The authors did not observe any intraoperative or postoperative complications. CONCLUSIONS: Surgical approach to stage 3 APROP refractory to laser photocoagulation could be effective and safe in order to avoid the progression of the disease.

Intravitreal triamcinolone acetonide: valuation of retinal thickness changes measured by optical coherence tomography in diffuse diabetic macular edema.

PURPOSE: The authors studied the efficacy of intravitreal triamcinolone acetonide in a case series of patients with diffuse diabetic macular edema without evidence of vitreous-macular traction refractory to laser photocoagulation. METHODS: Six eyes with clinically diffuse diabetic macular edema that failed to respond to at least two previous sessions of laser photocoagulation were included. The mean age of selected patients was 72.5+/-13.8 years, with a preoperative best-corrected visual acuity reduced to 1.48+/-0.18 logMar and a mean baseline intraocular pressure (IOP) of 15.17+/-2.64 mmHg. The authors also studied macular thickness measured by optical coherence tomography (OCT 2000 scanner, Humphrey Instruments, San Leandro, CA) - in the preoperative period it was 640.8+/-171.1 microm - and the fluorangiographic (Heidelberg Retina Angiograph, Heidelberg Engineering GmbH, Heidelberg, Germany) patterns, which showed pooling in tardy phases and leakage. Mean follow-up was 4 months. RESULTS: In each patient the authors observed a significant improvement, both functionally and anatomically. Mean best-corrected visual acuity increased in the postoperative period to 0.94+/-0.53 logMar. No patient showed decline of visual acuity at the end of follow-up. Base line macular thickness was reduced in the postoperative period to 312.2+/-157.65 microm measured by OCT and fluorangiographic patterns showed a reduction of pooling and of leakage. The most common complications described in the literature were not observed and the increase of mean IOP in the postoperative period to 18.76+/-5.72 mmHg was not significant. CONCLUSIONS: Intravitreal triamcinolone acetonide may decrease macular edema and improve visual acuity in eyes with diffuse diabetic macular edema.

Luxated intraocular lens fixation using anterior chamber slipknot of the haptic to the sclera: a simple procedure to fixate intraocular lens to the sclera.

PURPOSE: To describe a technique for suturing a luxated intraocular lens (IOL) in the vitreous cavity directly to the ciliary sulcus using intraocular slipknot without IOL extraction. DESIGN: Noncomparative interventional case series. MATERIALS AND METHODS: A three-port vitrectomy was performed in all cases. According to the Lewis procedure, two scleral flaps and relative sclerectomies were performed at 3 and 9 o'clock position. IOL was rescued from vitreous cavity by means of perfluorocarbon and stabilized in anterior chamber by intravitreal forceps. Corneal endothelium was preserved by a dispersive ophthalmic viscosurgical device coating. Double armed 10-0 polypropylene was introduced into the vitreous cavity through the 9 o'clock sclerotomy incision and both the needles were passed out of the eye by the 3-o'clock position sclerotomy, guided by a bent 27-gauge needle 1.5 mm from the limbus. Hooking the slipknot around the haptics of the IOL in the anterior chamber by means of vitreous forceps, the 10-0 polypropylene was pulled so that the IOL haptic was fixated onto the sulcus. The same procedure was used to fixate the opposite haptic to the ciliary sulcus at the opposite position. RESULTS: In all four cases, the IOL fixated stably and remained well positioned. No significant intraoperative or postoperative complications occurred. CONCLUSIONS: This technique enables secure fixation of the luxated IOL in the vitreous without extracting it.

Choroidal neovascularization secondary to vitrectomy for idiopathic epiretinal membrane: report of an unusual case.

PURPOSE: Epiretinal membranes (ERM) are a common finding in old patients. Pars plana vitrectomy is effective for removing ERM from the macula, but some postoperative complications are relatively frequent. In the present report, we describe a 73-year-old man in whom extrafoveal choroidal neovascularization developed four months after surgery. METHODS: Choroidal neovascularization was treated by argon laser photocoagulation. RESULTS: Six months after treatment, the choroidal neovascularization was obliterated, with no recurrence of ERM. CONCLUSIONS: Choroidal neovascularization can be an unusual complication of ERM surgery, and should be suspected in case of poor visual outcome or recurrence of symptoms.

Protein oxidation and lens opacity in humans.

PURPOSE: Oxidative damage to lens proteins is a major factor leading to cataract formation. It is of pathogenic importance to determine a threshold of protein oxidation over which opacification of the lens takes place. METHODS: Sixty-two lenses extracted from patients affected by idiopathic senile, diabetic, or myopic cataract were studied. Clear lenses were obtained from subjects undergoing enucleation (n = 10) or vitrectomy for giant retinal tears (n = 9), and were age- and sex-matched to those with cataract. The content of carbonyls and sulfhydryls (P-SH) in proteins in the lens was assessed using spectrophotometric assay. RESULTS: An age-associated inverse relation (P < 0.01) was noted in the content of P-SH, the concentrations of which were also inversely related (P < 0.03) to the content of protein carbonyls. These changes were more pronounced in cataracts than in clear lenses and in diabetic and myopic cataracts when compared with senile cataracts. The drop of P-SH concentration occurred earlier in diabetic and in myopic cataracts than in senile cataracts. The accumulation of protein carbonyls > 2 nmol/mg protein and the decrease of P-SH below 12 to 10 nmol/mg protein were always accompanied by lens opacification. CONCLUSIONS: Idiopathic senile, diabetic, and myopic cataractogenesis appear to be dependent on oxidative damage to lens proteins. This damage occurs earlier in myopic and diabetic patients. Values of P-SH below and protein carbonyls above their specific threshold were found to be predictive for the presence of cataract. Because increased oxidation was observed in clear lenses removed from myopic and diabetic subjects, oxidation may be involved in the pathogenesis of these forms of human cataract.

Pars plana vitrectomy in diabetic macular edema.

PURPOSE: To ascertain the association between the improvement of diabetic macular edema and increased visual acuity after pars plana vitrectomy. METHODS: From January 1994 to December 1996 we prospectively studied 18 patients (18 eyes, 7 women and 11 men, mean age 52 years, range 37-68) with type II diabetes and clinically significant macular edema. One group was composed of 9 patients presenting diffuse macular edema (DME); a second group with 9 patients presented cystoid macular edema (CME). All patients underwent pars plana vitrectomy. RESULTS: Preoperative Snellen visual acuity was 20/143 in DME and 20/441 in CME. In both groups vision increased to 20/136 and 20/205, respectively, postoperatively. For the DME this difference was statistically significant (p<0.05) at 1 month after the surgery, but vision decreased again after 10 months reaching preoperative values. CONCLUSIONS: Our results suggest that pars plana vitrectomy for diabetic macular edema may increase visual acuity in diffuse macular edema, although this increase is only short lived.

Oxidative retinal products and ocular damages in diabetic patients.

Several evidences suggest a retinal participation to the genesis of diabetic eye complications by means of an increased free radical production at this level. However, no direct proof exists that this happens in humans in vivo. Therefore, the concentrations of malondialdehyde (MDA), carbonyl and sulfhydryl (P-SH) proteins, and vitamin E have been assessed in the subretinal fluid (SF) of patients affected by retinal detachment. Diabetic (n = 19) and nondiabetic (n = 21 ) subjects with comparable age, degree of myopia, and duration of the retinal detachment were considered. A control group of n = 7 subjects was included. The SF was collected after drainage during surgery. The concentrations of total proteins, P-SH, and carbonyl proteins were determined with spectrophotometric methods; the levels of MDA and vitamin E were measured by HPLC. The protein concentration in SF did not differ among groups. A higher concentration of MDA (p < .01) and carbonyl proteins (p < .02) were found in diabetic compared to nondiabetic subjects. Diabetic patients also showed a lower content of P-SH (p < .002) and vitamin E (p < .001) compared to nondiabetic subjects. All these parameters were more markedly altered in patients affected by proliferative diabetic retinopathy and significantly differed between patients and control subjects. In conclusion, oxidative events are associated with retinal detachment in humans. This evidence strongly suggests that the retina is a source of free radical production under certain conditions, such as diabetes.

Oxidative protein damage in human diabetic eye: evidence of a retinal participation.

Considerable evidence indicates that the maintenance of protein redox status is of fundamental importance for cell function, whereas structural changes in proteins are considered to be among the molecular mechanisms leading to diabetic complications. In this study, protein redox status and antioxidant activity were investigated in the lens and vitreous of diabetic and nondiabetic subjects. A significantly lower content of sulphydryl proteins was found in lens and vitreous of diabetic patients than in those of non-diabetic and control subjects. Moreover, an increased formation of protein-bound free sulphydryls and carbonyl proteins, indices of oxidative damage to proteins, was noted in diabetic patients. All these parameters were shown to be altered particularly when diabetes was complicated with retinal alterations. In addition, glutathione peroxidase activity and ascorbic acid levels, known to exert important antioxidant functions in the eye compartment, were found to be significantly decreased in the lens of diabetic patients, especially in the presence of retinal damage. This study indicates an alteration of protein redox status in subjects affected by diabetes mellitus; lens and vitreous proteins were found to be oxidized to a greater extent in the presence of retinal disease, together with a marked decrease of eye antioxidant systems. These results suggest that oxidative events are involved in the onset of diabetic eye complications, in which the decrease in free radical scavengers was shown to be associated with the oxidation of vitreous and lens proteins. Protein oxidation may, therefore, represent an important mechanism in the onset of eye complications in diabetic patients.

Role of lipid peroxidation in the pathogenesis of myopic and senile cataract.

AIMS/BACKGROUND: Increased production of free radicals, consumption of antioxidant, and oxidation of unsaturated lipids have been observed recently in cataractous lenses and active participation of the retina in human cataractogenesis has been proposed. To verify this hypothesis, the total (GSH) and oxidised (GSSG) glutathione concentrations were assayed in the lens and the malondialdehyde (MDA) levels assayed in the vitreous and in the lens of normal controls and patients with senile or myopic cataract. METHODS: The study was conducted on 34 lenses (nucleus and epinucleus) (nine clear lenses, 14 lenses with idiopathic senile cataract, and 11 lenses affected by severe myopic cataract) and vitreous of 19 (seven non-myopic, seven myopic, and five control) subjects. Glutathione determination was performed following the method of Reed, while malondialdehyde was assayed using a modification of the method of Dahle. RESULTS: Cataractous lenses showed a decreased content of GSH and increased concentration of GSSG compared with clear lenses. A higher oxidative consumption of GSH was found in myopic cataracts compared with senile ones. Also, increased levels of MDA were observed both in cataractous lenses and in the vitreous of myopic patients compared with the control and the senile ones. CONCLUSION: The observed alterations strongly suggest that retinal lipid peroxidation might play a key role in human cataractogenesis, especially in the myopic type.

Human diabetic cataract: role of lipid peroxidation.

To test whether impaired glutathione redox status may be related to lens oxidative damage in humans, we measured glutathione (total and oxidised forms) and malondialdehyde, a lipid peroxidation product, in clear lenses and diabetic and non-diabetic cataracts. Diabetic cataracts were divided into 2 subgroups with either intact or abnormal haemo-ocular barrier as evaluated by preoperative iridography. Decreased total glutathione values were observed in cataractous (diabetic and non-diabetic) as compared to clear lenses (p < 0.001), whereas enhanced oxidised glutathione levels were found in diabetic caracts as compared to non-diabetic ones and clear lenses (p < 0.001). Malondialdehyde concentrations were significantly higher in all types of cataracts, especially myopic and diabetic ones, than in clear lenses (p < 0.001). Moreover, malondialdehyde levels in diabetic lenses were inversely correlated with total glutathione (r = 0.80; p < 0.001) and linearly correlated with oxidised glutathione values (r = 0.76; p < 0.001). Finally, glutathione redox status was found to be more seriously impaired in lenses from diabetic patients with abnormal than intact haemo-ocular barrier. These data suggest a contributory role of lipid peroxidation and glutathione oxidation and consumption in the pathogenesis of cataract, especially in diabetic lenses with haemo-ocular barrier abnormality.

[Effect of scleral buckling on ocular tone]. / Influenza del cerchiaggio sul tono oculare.

Having examined in literature the intraocular pressure changings due to periocular encirclement, the Authors analyse a casenstry of 135 eyeballs in which a silicone band encirclement was performed. They conclude emphasizing the hypotonizing action of this technique, due to ciliary body ischemia, hypothesizing the use of this surgical technique in case of neovascular glaucoma.